Process for the production of metallic beryllium



Patented Dec. 24, 1929 PATENT OFFICE WILHELM KROLL, or LUXEMBURG, LUXEMBURG PROCESS FOR THE PRODUCTION OF METALLIC BERYLLIUM No Drawing. Application filed September 26, 1927, Serial No. 222,211, and in Germany September 28, 1926.

The present invention relates to a new useful process for the production of compact metallic beryllium.

Hitherto two kinds of processes have been used for the production of metallic beryllium, namely the chemical and the electrochemical processes. 7

In the chemical process beryllium chloride was reduced by an alkali metal. In this way 10 spangles or scales of the metal are obtained which must be melted down into compact pieces in vacuo.

The only-one of the electro-metallurgical processes which has been of any practical use is that one in which an electrolyte consisting of barium beryllium fluoride is subjected at about 1300 C. to electrolysis using cathodes which provide a good contact. By this process it is possible to obtain compact beryllium in comparatively large pieces. Unfortunately electrolysis requires a relatively large consumption of current and a considerable part of the beryllium is lost owing tothe volatilization of the fluoride.

After thorough investigation of the conditions prevailing in the case of electrolysis I made the present invention according to which metallic beryllium can be obtained in a much simpler way by chemical decomposition. The reactions selected for the decomposition are based on the greater aflinity of magnesium or of the earth alkali metals or of lithium for fluorine, so that beryllium fluoride can be decomposed in the simplest possible manner, and beryllium in the metallic form is set free. The decomposition reaction between the said metals and the beryllium fluoride is so violent that this reaction can-.

duct the reduction of the beryllium that beryllium completely free from any earth alkali metal, magnesium or 'lithium shall be obtained, provision must be made for a certain excess of beryllium fluoride or else the impure metallic beryllium obtained by the first decomposition must be decomposed again several times with fresh salt.

Erample. 150 grams of MgF BelE were caused to react in a molten state with 20 grams of magnesium. The temperature rose above the melting point of beryllium so that compact metallic beryllium could be obtained. This however still contained about 5% of magnesium. By repeatedly decomposing the metallic beryllium obtained with grams of the same salt I was able to obtain at 1300 C. perfectly pure metallic beryllium. If calcium be used for reduction, it is preferable to use calcium fluoride as the diluent for the beryllium fluoride. Metallic lithium which behaves similarly to the earth alkali metals may be used instead of magnesium or calcium for reduction but any alkali metal other than lithium cannot be used. On the. other hand care must be taken to see'that the molten mass contains only a little alkali fluoride as otherwise the reaction will be too violent and the alkali metal escapes in the form of vapour.

A number of other salts have been found to be satisfactory diluents for the beryllium fluoride such salts being preferably halogen compounds of the earth alkali metals. Ifsuch metallic salts be added to the mixture of salts. alloys of beryllium with the metal forming the base of these added salts will be formed. Thus for example aluminium-beryllium can be obtained by the decomposition of beryllium aluminium magnesium fluoride by metallic magnesium. By correctly selecting the salt components aluminium-beryllium alloys of high p'recentage and free from magnesium can be obtained. The same result is obtained if the metal with which the beryllium is to be alloyed be added to the bath not in the form of a metallic salt but in the form of any alloy with an'earth alkali metal or as a pure metal. Thus aluminium-beryllium can be obtained from calcium-aluminium using beryllium fluoride asthe reacting salt, Berylli 1 loys of copper and iron are prepared in the same way.

The metallic beryllium obtained 'by the method above described can vbe purified or refinedin a simple manner by superheating attended by difficulties inthat the choice of suitable crucibles is a very restricted one. The earth alkali metals or the beryllium react with most of the substances which can be used and the fused fluorides assist the reaction to a very great extent. It was found that the reactions can be carried out in crucibles composed of fused alumina or magnesia or of beryllium oxide. It has however also been found of advantage to carry out the fusion in crucibles of pure graphite and to pour the fused mass into a vessel having Water cooled walls: and in which it is caused to react with magnesium or other earth alkali metals and can if necessary be kept hot by means of electrodes which provide a good contact. If the temperature be correctly selected and the composition of the mixture of salts is correct, the heatof combination of the magnesium with fluorine, is suflicient to keep the reaction going and to raise the temperature to such a degree that compact fused metallic beryllium can be obtained.

- In comparison with the electrolytic method the hereinbefore described chemical decomposition method possesses the great advantage that compact metallic beryllium is obtained in almost theoretical yield directly and in the shortest possible time andwithout any appreciable loss of beryllium .fluoride.

Where in the appended claims I have mentioned an earth alkali metal, I desire this term to be interpreted as covering or including the equivalents mentioned above, that is to say, magnesium or lithium.

What I claim as-my invention and desir to besecured by Letters Patent is: A

1. The process for the production of'compact metallic beryllium which consists in bringing to reaction fluorides of beryllium and at least one earth alkali metal free from water as a molten fused mass and at, a temperature of at least about 1300. C., taking away the product of the reaction and melting it once more together with beryllium conta-ining fluorides.

2. 'The process for the production of compact metallic beryllium which consists in bringing to reaction. fluorides of beryllium and at least one earth alkali metal free from bringing to reaction an excess of a beryllium fluoride compound free from water and at least one earth alkali metal, as a molten fused mass at a temperature of at least about l300 0., taking away the product of the reaction and melting it once more together with beryllium containing fluorides. I

In testimony whereof I afiix my signature.

WILHELM KROLL. 

